This invention relates to power generating equipment to provide a source of fluid, preferably hydraulic, power, and, more specifically, the invention relates to free piston engine pumps for generating such fluid power.
As will be appreciated by those familiar with hydraulic power systems, such systems are desirably highly efficient, low in cost, compact, light in weight and emit to the atmosphere a low level of pollutants. However, known systems which attempt to conform to these requirements are characterized by deficiencies in one or more respects, including, for example, the requirement of costly maintenance and resulting in certain inconveniences to the user.
A free piston engine pump unit which generates hydraulic power in response to internal combustion and which provides improvements over prior hydraulic power generating equipment is disclosed in U.S. Pat. No. 4,087,205, the disclosure of which is hereby incorporated by references. In such unit a main reciprocating member (hereinafter sometimes referred to as "member"), which includes a pair of reciprocating, mechanically connected power pistons and pump pistons, is movable in respective bores of a housing in response to internal combustion occurring in opposite combustion chambers to pump fluid from respective opposite pump chambers. Check valves control low pressure fluid flow into and high pressure fluid flow out from respective pump chambers, and a series of one-way valves controls fluid flow within the unit, which also develops a pressurized air supply to support combustion in the combustion chambers. A cycling valve assembly supplies fluid alternately to the respective pump chambers to force movement of the member during start-up of the unit: direct mechanical connections by toggle pins feed back to the cycling valve assembly information concerning the member to control such fluid flow during start-up. Several arrangements for injecting fuel into the respective combustion chambers also are disclosed in such patent.